Android : Changing size of view/canvas at runtime

i am programming a view which is inside a scrollview. Everything inside the view is drawn using onDraw(). The view shows an object which is custom-build for a day. With two buttons, you can change the selected day forwards/backwards, but the problem is, that each day needs its own specific height. Is there a method to change the size of a view on at runtime or can i use onMeasure() before onDraw()?